The correct answer is letter D. distance to a star.
In astrophysics, M = m - 5 log(d/10)
where
m - apparent magnitude
<span>M - absolute magnitude </span>
<span>m - apparent magnitude </span>
<span>d - distance measured in parsec </span>
c well actually I remember being tought this but I cant remember it 100
<span>x=<span><span>3<span> or </span></span>x</span></span>=<span><span>−1/</span><span>2 let me know if it was wrong </span></span>
According to Henderson–Hasselbalch Equation,
pH = pKa + log [Lactate] / [Lactic Acid]
As,
Ka of Lactic Acid = 1.38 × 10⁻⁴
pKa = -log Ka
pKa = -log 1.38 × 10⁻⁴
pKa = 3.86
So,
pH = 3.86 + log [0.10] / [0.13]
pH = 4.74 + log 0.769
pH = 4.74 - 0.11
pH = 4.63